The long-term objective of this project is to develop a three-dimensional dosimeter for verifying complex conformal radiotherapeutic treatment. The overall criteria is that the dosimeter formulation must be as sensitive as but more stable than the currently available dosimeter, BANG-3 from MGS. An extensive screening study of radiolytically oxidizable and reducible compounds in aqueous gels and nonaqueous polymers was performed. From these studies we have identified several formulations that should meet the criteria of being equivalent to and more stable than the BANG-3 dosimeter. Based on these preliminary results our experimental plan calls for additional diffusion studies using a micro beam tomographic optical scanner. In addition, the color intensity versus absorbed dose, effect of concentration on G value, dependence of photon energy and dose rate, and signal stability will all be measured using a spectrophotometer at 632 nm. If the above criteria are met a full scale dosimeter will be irradiated and evaluated on a tomographic optical scanning system. PROPOSED COMMERCIAL APPLICATION: There is a need to develop a sensitive and stable 3-D radiation dosimeter to verify complex radiotherapeutic treatment plans, particularl, for the newer treatment plans such as IMRT. Even though it is difficult to predict the annual number of conformal radiotherapies performed it is clearly growing in number. There are over 600,000 patients annually requiring radiation therapy in USA.